Question

please explain and answer with proper steps

Answer 1

The concentration will always be uniform throughout.

so each of the 1000 drops will have the same concentration of 0.1M.

but there is something that will and must change, which is the number of moles in each of these drops. 

Total number of millimoles of NaCl = molarity x volume(in ml)
                                                       = 0.1 x 10
                                                       = 1 millimole

since 10ml is divided into 1000 drops each drop will have a volume of 0.01ml

The number of millimoles in each drop = 0.1 x 0.01
                                                              = 0.001 millimoles

Thus we see that the concentration of the solution remains the same always unless you add something from the outside, but the number of moles will change with change in volume so as to keep the concentration uniform or conatant.